Atlantic Ocean: Atlantic coast from Scandinavia to Morocco; Baltic, Black and Mediterranean Seas; rivers of North Atlantic, Baltic and Mediterranean seas (Ref. 172, Ref. 51442). Continuous introductions to Asia and South and Central America. Spawning area in western Atlantic (Sargasso Sea). At least one country reports adverse ecological impact after introduction. Recent genomic DNA studies show that the European eel exhibits isolation by distance, implying that non-random mating and restricted gene flow among eels from different location exists (Ref. 43723). The existence of 3 genetically distinct sub-populations is suggested: a Northern European subpopulation (consisting mainly of the Icelandic stocks); a Western European subpopulation (including the Baltic, the Mediterranean and Black Sea); a Southern sub-population (including stocks of Morocco) (Ref. 43723, 89139).